With a rapid progress in multimedia technology in recent years, digital images have been widely used, and therefore demands for image processing devices from consumers are on the rise day by day. Various digital image products, such as web cameras, digital cameras, and smart phones, retrieve images through image sensors.
A complementary metal oxide semiconductor (CMOS) image sensing element may be designed to be curved to change its optical characteristics, so as to reduce the number of corresponding lenses required and to achieve miniaturization of image sensing modules. Generally speaking, the image sensing element that has not yet been curved is disposed on an arc surface of a substrate. The substrate has a through hole at the arc surface, and the through hole is below the image sensing element. Then, the image sensing element is forced to be curved downwards and attached to the arc surface of the substrate by extracting air through the through hole, so as to obtain a curved image sensing element. Nevertheless, the through hole arranged for air extraction has to be formed in the substrate first, which requires more time and effort as a result. Moreover, the structure of the substrate is not strong enough to firmly support the image sensing element because of the through hole, thus leading to unexpected deformation at the through hole of the image sensing element. In addition, in a general image sensing module, since the image sensing element is not encapsulated by any adhesive, the image sensing element is prone to be attached by foreign substances (e.g., dusts in the environment) during its manufacture, and the quality of the image sensing module is thus reduced.